Prevent ESLint errors from aborting build during development

Not being able to build using the development server whenever there are ESLint errors is a pain.

This change updates react-scripts to 4.0.3 in order to make the option ESLINT_NO_DEV_ERRORS available. This option makes all eslint errors appear as warnings during dev build. It is enabled in our .env file.

requested review from @imretoth and @zoltanrunyo

assigned to @johnsparger

changed the description

changed title from Stop ESLint errors from aborting build during development to Prevent ESLint errors from aborting build during development

approved this merge request

mentioned in commit 4e476942

merged